Superhydrophobic and superhydrophilic surfaces with MoO_x sub micron structures

摘要

Presented is an investigation of surface morphology of arrayed MoO_x structures with increasing aspect ratios, and their resultant superhydrophillic, and their modified superhydrophobic properties. Molybdenum oxide (MoO_x) submicron structures were grown on lithium niobate (LiNbO_3) substrates via the thermal evaporation of MoO_3 nanopowder at 750°C in a horizontal tube furnace. A mixture of 90% argon and 10% oxygen was introduced into the thermal evaporation tube at flow rate of 1L/min. This resulted in the formation of a white film which consisted of submicron tabular structures. Scanning electron micrographs revealed that the tabular molybdenum oxide grew in arrays 80-100° with respect to the plane of the substrate, with tabular structures with a thickness of approx 0.5 - 1.5μm. Initial testing of MoO_x structures revealed that they were extremely super hydrophilic. Such MoO_x arrays were coated with fluoropolymer Teflon, deposited using the RF sputtering technique. The addition of a semi-conformal Teflon layer effectively converts the superhydrophilic MoO_x layer into a superhydrophobic surface. These superhydrophobic surfaces exhibit contact angles with aqueous media in excess of 150°. Such surfaces can be utilized for the selective adsorption and desorption of protein or pharmacokinetic molecules, with applications in drug delivery and biomedical systems.